The present invention relates to a device by which ribbons of small transverse dimensions are spliced automatically.
In the art field of packaging and wrapping related to consumer products, in particular cigarettes or similar articles, the finished packet is enveloped typically in a transparent overwrapping material. It is usual with wrapped commodities of this type to apply a ribbon of small transverse dimensions directly to the outermost wrappings, such that when the moment comes for the packet to be opened, the wrapping can be torn swiftly along a predetermined and well-defined break line.
Automatic machines with the ability to fashion such wrappings are designed to use this type of ribbon; successive ribbons are decoiled each in turn from a respective roll, and, given the slender proportions of the ribbon material, the rolls in question are notably slow to deplete when compared to the rolls from which the overwrapping material is decoiled. As a result, the intervals at which the rolls of ribbon need to be replaced are relatively lengthy, and the operation of joining the trailing end of the depleted ribbon to the leading end of the new ribbon is relatively infrequent. In the context of the overall efficiency of such wrapping machines, therefore, an entirely manual type of changeover has often been considered acceptable, although more recently, as machines have become capable of higher operating speeds, the need has arisen to effect even these changeover operations automatically and as swiftly as possible, to the end of minimizing any delays or down time attributable to the change procedure. Consequently, it has been necessary to concentrate also on the actual step of splicing the ribbons, seeking to obtain still greater precision and speed.
To this end, UK Patent Publication GB 2 260 532 discloses a device by which ribbons of the type in question are spliced automatically. The splice is effected directly by jointing means comprising an element on which the leading end of the new ribbon is positioned and restrained, also a reference and reaction element, disposed on opposite sides of the ribbon in use and capable of movement toward one another to a point at which the leading end of the new ribbon and the trailing end of the depleted ribbon are brought fully into contact. Clearly, in order to perform the splice, which can be effected by heat-sealing or gumming, the jointing means must trap and immobilize the ribbons and thus interrupt their feed motion. To overcome this interruption in the progress of the ribbon, which is drawn forward by suitable drive means nearer to the point of use, it is indispensable to incorporate a tension loop at some stage between the splicing device and the drive means. Nonetheless, the loop does not prevent a reduction in the operating speed of the wrapping machine, which reduces whenever the tension loop is activated.
The object of the present invention is to provide a device for splicing ribbons such as will operate without interrupting the feed motion of the ribbon when activated, and at all events without causing any variation in the rate of the feed, so that the wrapping machine by which the ribbon is utilized can continue to operate at its normal speed.
A further object of the present invention is to provide a splicing device such as will be simple and economical in construction, as well as easy and practical to use.